Alarms ? wired or wireless

[smeeagain]

You may remember earlier in the thread hearing various comments about how wireless systems worked and then you specifically asked if anyone could give examples of a particular system instead of general comments. In response to your request of conctrete examples I gave the knowledge of how a particular system I knew well solved wireless issues.

Now you are questioning why I was specific?

You make a good double act.

 

[smeeagain]

With regard to wireless, there is a lot of comment as to how it does this, that the other. This should be seen as nothing more than comment on the subject in general. Nothing specific and pertinent to a particular system and it's methods of operation have been stated therefore no accurate conclusion can be made on it's capabilities from these comments.

 

[olbas]

You're missing the point. All you have said is the power saving of the red led - not how it works. Worryingly, and based on your comments that you actually charge people, it would seem you have little to no knowledge of the everyday practical/regulatory reasons the led behaves as it does.

Have a word with tech support, they'll be able to help you.

You might be inclined to check the detail of that low cost insurance you took out too.

 

[Plumbob66]

wireless alarms? can they not be manipulated like wireless networks, or wireless central locking on cars?

 

[bernardgreen]

Power is saved because when in sleep mode the red leds don't come on therefore saving the power used to illuminate them.

In alarm set state assuming no intruders the sensors are not detecting movement so are not lighting up or transmitting signals so are running at low power.

What is the power requirement to operate the sensor. ?

Is the sensor definately continuously active ( when not in sleep mode ) ?

If there is a jamming signal in the are of the bell box then some designs will sound the alarm. For how a long time does the jamming signal have to be present before the box considers it is disconnected and sounds the alarm ? It is "disconnected" from the control panel as the communication link has be cut by the jamming. How many such alarms can the battery in the bell box cope with ?

 

[bernardgreen]

wireless alarms? can they not be manipulated like wireless networks, or wireless central locking on cars?

Yes they can be manipulated. Nothing using wireless is 100% secure against manipulation from an external source. The difference is the amount of resiliance to manipulation and the way the system reacts to manipulation of a type it cannot cope with,

 

[smeeagain]

I have to say Bernard obviously as noted I can only specify how the system I have knowledge of works based purely upon its use in service and the limited information available in the public manuals.

I don't know how the GSD system works or what algorithms they have used and that is the one that has been approved for Grade 3 applications.

I do know that the Yale system activates the alarm when it senses jamming.

Now how it senses jamming I do not know.

The Yale systems can be configured in two ways. One with the siren itself as the master device and another where the siren is a slave device to the control panel.
I suspect both systems use a different method but I could not confirm this.

There are several ways for jamming to by hypothetically detected.
Each sensor has its own individual ID. every yale device out of the factory has a different Id.
You could use this as the basis as anti jamming. ie any carrier signal at the working frequency that doesn't include its Id is percieved as a jamming attempt.
I don't actually think this method is used however.
I am into hypothesising here but given that we allready know each device continually either constantly or intermitently send out its id hence the control panel being able to tell when a device has dropped from the system then jamming could be deduced when all enrolled sensors fail to 'report in' or no reports are recieved within X timeframe.

As I say though thats all hypothesis from my point.
I am assuming the Yale is not a two way system of course.
In a two way system a panel could send 'request a response' signals at random intervals to which the sensors reply 'yes I'm here'
Jamming could be percieved when either a carrier signal fails to carry an id or no response is recieved from the enrolled devices.

Of course it could be a combination of the two. A carrier without ID and a loss of response from the devices concurrently could be the logic used to detect jamming.

To answer the other poster of the humble Yale detects jamming then it activates the alarm.

In answer to your other question how many times could tha alarm respond to jamming..
It depends on the alarm settings you have used for your alarm.
The alarms can be set to activate anywhere from 3 minutes to 15 minutes.
Jamming would set the alarm off for whatever time you had programmed your system for.
If a thief wants to continually set off a system by jamming in an effort to drain the alarm batteries then he may have to do so for anything from six to 18 attempts.
This means at least almost two hours worth of siren activation.
This notwithstanding the attention it has drawn from neighbours or even the owners if they have the telecommunicating panel fitted.

 

[Atilla]

I don't know how the GSD system works or what algorithms they have used and that is the one that has been approved for Grade 3 applications.

did you not listen last time?

products are not "approved" for any grade, were working on it but no one wants the job.

Please please explain how you think a passive device can also be an active device as required to be certified as G3?

 

[bernardgreen]

Now how it senses jamming I do not know.

If you are installing these and also advising customers about their use then you should make the effort to obtain a basic knowledge of jamming and how it will affect the systems you are installing.


Jamming of a radio controlled device is most commonly detected by the radio receiver receiving a signal on the radio frequency that does not match the protocol of the system. Or in other words if the radio channel is continuously busy but no valid or understandable data is being received then the channel is being jammed.

If continuous then it is jamming. if intermittant then it is commonly referred to as blocking. Blocking frequently happens as the result of another legal system nearby using the radio channel. This could be another alarm system or a vehicle key fob or any other equipment that is allowed to legally operate on that radio channel.

Blocking should not be a problem as the system can retry when the blocking signal has ended.

The problem for the equipment design team is to decide what is blocking and can be ignored ( other than re-transmitting the message ) and what is jamming and has to create an alarm.

Then there is random jamming and "informed" jamming.

Random has garbage as data messages and therefore easy to recognise as jamming.

Informed has data messages that the sytem will see as valid messages for other modules in the system and therefore cannot immediately be identified as jamming. The designer has to make the system able to recognise when infomed jamming is occuring. This is further complicated if one or more similar alarm systems are operating close together. Genuine messages from one system will affect the other(s) and the decisions about jamming, blocking or acceptable other system messages become more compromised.

A system that works well today may become un-reliable or even un-usable if a neighbour then installs a wireless system. Provide his system is operating correctly you cannot ask him to stop using it.

In short, if it possible to install a wired system then choose wired.

 

[smeeagain]

Hi Bernard,
Thanks for your update.
I do know that the Yale will activate when jammed but as mentioned didn't know the actual technical algorithm used.
I did in my previous post summise the methods used which relate directly to the explanation you gave although I added some other probables as well.
Wired is preferable as you say but there are many reasons why people may still wish to choose a wireless.
Budget and practicalities being the major concerns to the private homeowner.

 

[bernardgreen]

so you will still fit something even though it isnt fit for purpose? anything for a quick buck eh?

While I remain concerned about the reliability of wireless alarms I do see they can have some value.

And I would think that one that has been installed by a person with some experience of them is likely to be more effective ( less un-reliable ) than one installed first time by a DIYer without experience of the problems involved by wireless systems.

 

[smeeagain]

So you will still fit something even though it isnt fit for purpose? anything for a quick buck eh?

I never said that at all. Troll.

Incidentally , just got back from installing a safe for a chap whose home alarm no longer works and the original installer of the 4 yr old system cannot be traced after a company buy out and change.

There is actually an argument that all alarms are flawed in principal wether wired or wireless.

A fitted safe that has been attack tested by the Police and certified by insurance companies is in actual fact of more practical use than an alarm.

However it is a surprisingly hard sell to consumers who would prefer to have an alarm and leave their valuables in every drawer or worktop than have the neccessary discipline to store their stuff.

Something we do naturally on holiday (using the room safe) is an alien concept at home.

I know what given half an hour would defend valuables better.

 

[smeeagain]

Have you had enhanced vetting?

Yes oh yes...

July 2010 here we come . . .no more plumbers , electricians , alarms or jack as everyone is labelled unfit.. what a govt

Have you had yours done.
Spoke to the ISA this week as it happens and I am not on the banned list so I am OK. are you?

 

[olbas]

So, no, he hasn't then.

 

[bernardgreen]

The LED indication on the front of the PIR sensor is an essential diagnostic tool with a wireless connected system. Without it it would be impossible to determine the cause of a failure in the testing of the system ( as in a walk test ).

If during, the walk test of a wired system, the control panel does not react to the "motion detected " signal from a sensor then at the control panel the technician can measure the voltage on the zone input terminals for that sensor. From that measusrement the techniciancan can simple determine whether the sensor has failed to operate or the panel has failed to react to the sensor.

With a wireless system there are no hardware zone terminals to measure so diagnostic indicators on sensors are essential for fault finding.